An ink jet recording method is a printing method wherewith droplets of an ink composition are sent into flight and made to adhere to a recording medium such as paper. This method is characterized in that therewith it is possible to print images of high resolution and high quality at high speed with a comparatively inexpensive apparatus.
Based on such an ink jet recording method as this, color images are being formed using a plurality of color ink compositions. Color image formation is being performed with ink sets comprising a yellow (Y) ink composition, a magenta (M) ink composition, and a cyan (C) ink composition to make three colors of ink, or with an ink set wherein a black (K) ink composition is added to those noted above to make four colors of ink.
Images exhibiting a silver chloride photographic tone that are recorded using an ink set comprising those four colors of inks have many highlight portions where the ink dots are conspicuous, and color images of high picture quality cannot be output. Hence, in order to resolve this problem, an ink set has been developed in recent years that comprises a plurality of dark and light inks that, while being mutually the same color, have different color densities. This ink set comprises, for example, four colors of ink, namely K, C, M, and Y, that are dark ink compositions, and four colors of ink that are light inks, namely light black (Lk), light cyan (Lc), light magenta (Lm), and light yellow (Ly). The ink sets comprising a plurality of these dark and light inks effect coloring by varying the amount of colorant striking the recording medium per unit area thereof (duty level). When recording is done using an ink set such as this, it becomes possible to output color images of a high quality comparable to silver chloride photographs, wherein the grainy feel caused by ink dots is diminished.
However, with an ink set comprising such dark and light inks, when the duty level is made higher or lower, the permeability of the ink at the surface of the recording medium also varies, as a consequence whereof there has been a problem in that ink builds up on the surface of the recording medium, is scattered, and dries, so that a condition of “roughness” readily develops.
Also, of the pigment inks, color pigment inks (i.e. C, M, Y, Lc, and Lm), but particularly the Lc color and Lm color pigment inks, do not exhibit adequate light resistance compared to the dark color inks. This has led to a problem in that, in the text and/or images formed in the recording noted earlier, those portions of the recording done with such Lc color and/or Lm color ink exhibit color fading over time, whereupon 0beauty is compromised in image printings as compared to silver chloride photographs.
Accordingly, an object of the present invention is to provide an ink set, together with an ink jet recording method and recording using such, wherewith high quality images can be obtained wherein no roughness occurs, and ink permeability is uniform even when the duty level is varied.
Another object of the present invention is to provide an ink set for ink jet recording that is capable of providing printed matter wherein the text and/or images formed using Lc color and/or Lm color water-based pigment inks, on a recording medium, but particularly on special paper, exhibit outstanding light resistance.